1. Field of the Invention
The present invention is generally related to an outboard motor with an undercowl plenum chamber that directs air along two parallel paths prior to combining the two paths together to supply air to an air intake manifold of an engine.
2. Description of the Prior Art
Many different cowl and undercowl structures are known to those skilled in the art for receiving air through an opening in a cowl and directing that air to various regions within the cavity of the cowl.
U.S. Pat. No. 4,860,703, which issued to Boda et al. on Aug. 29, 1989, discloses a cowl assembly with water resistant air intake duct and sealing. An outboard marine motor housed by a cowl assembly has an upper cowl section and a lower cowl section and includes various features for improving the structural integrity of the cowl assembly and for providing a water resistant seal at the joint between the cowl sections and at various points of entry of cables and other mechanical devices. An improved air intake duct prevents the entry of water into the interior cavity of the cowl assembly.
U.S. Pat. No. 5,119,778, which issued to Corbett on Jun. 9, 1992, discloses a tuned intake air system for a rotary engine. The system is intended for use in an outboard motor and includes a plenum chamber mounted on the rear of the engine directly against the exhaust manifold, which plenum chamber receives cooling air discharged from the engine. Air from the plenum chamber is directed into an elongated outlet conduit having an extended tuned length to provide an optimum pulsed air flow to the combustion air inlet of the engine.
U.S. Pat. No. 5,573,436, which issued to Trudeau et al. on Nov. 12, 1996, describes a semi-submersible outboard motor cover with air passage. A particular embodiment of the cover is formed by a generally hollow shell having an open side. An air passage is located opposite the opened side at an upper portion of the shell. A baffle extends from an upper inner portion of the shell to an elevation below the air passage and is disposed generally opposite the air passage.
U.S. Pat. No. 5,873,755, which issued to Takahashi et al. on Feb. 23, 1999, describes a cowling for an outboard motor. The cowling has at least one intake vent positioned therein and includes an engine cover which defines an isolated intake air path from the vent across a top end of the engine to an engine air intake. The cover also defines a chamber in which a flywheel rotated by the crankshaft at the top end of the engine is positioned.
U.S. Pat. No. 5,996,546 which issued to Kollmann et al. on Dec. 7, 1999, discloses an integrated flywheel cover and air conduit passages. A cover for an outboard motor is provided to protect an operator from a flywheel. The cover is disposed under the cowl of the outboard motor. The cover is made of a generally rigid material, such as plastic, with first and second sheets being associated together to form conduits with openings extending therefrom.
U.S. Pat. No. 6,302,749, which issued to Tawa et al. on Oct. 16, 2001, describes an outboard motor that has a first case member and a second case member connected to the first case member to form an enclosure having an inner space in which is mounted an engine. The first case member has an air intake hole for taking air into the inner space and a vent hole for exhausting the air after it circulates in the inner space to cool the interior of the engine.
U.S. Pat. No. 6,358,105, which issued to Isogawa et al. on Mar. 19, 2002, describes a cowling arrangement for an outboard motor. The arrangement includes a flywheel cover and cowling that incorporates upwardly and downwardly extending ribs which are positioned along an air path between the air vent of the outboard motor and the throttle body of the motor. These ribs act as labyrinth-type seals which prevent water entering the air vent from contacting the throttle body.
U.S. Pat. No. 6,383,044, which issued to Nemoto et al. on May 7, 2002, describes an outboard motor that has a first passage for supplying air from above the generator and a second passage for supplying air from below the generator, so as to cool the generator.
U.S. Pat. No. 6,413,131, which issued to Phillips et al. on Jul. 2, 2002, discloses an air flow system for an outboard motor. The outboard motor is provided with an air duct located within the cavity of a cowl of an outboard motor. The air duct defines a chamber within it in association with first and second openings that allow heated air to flow, through the creation of convection currents, out of the engine compartment under a cowl. This convection flow removes heat from the fuel system components and reduces the likelihood that vapor lock will occur subsequent to the use of an internal combustion engine that is followed by turning the engine off.
U.S. Pat. No. 6,645,022, which issued to Tsubouchi et al. on Nov. 11, 2003, describes an outboard motor which comprises an engine cover having an air intake opening for taking in air, an engine disposed in the engine cover, and an AC generator disposed in the engine cover for generating electricity to drive the engine. A cooling air guide member is disposed in the engine cover for guiding the air taken in by the air intake opening towards the AC generator. The cooling air guide member has a bottom wall, a pair of side walls extending upwardly from opposite side edges of the bottom wall, and an opening extending through the bottom wall so that the air taken in by the intake opening is guided by the side walls and the bottom wall to flow through the opening to cool the AC generator.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
As described above in the prior art, it is well known to those skilled in the art that air must be appropriately directed under the cowl of the outboard motor to efficiently cool certain components. Typically, an AC generator or alternator benefits from additional cooling by this air flow under the cowl. It would therefore be significantly beneficial if a simple and efficient way could be provided to direct air, which flows into the cowl, to an air intake manifold of an engine while also providing a cooling air flow in thermal communication with the generator or alternator. It would also be beneficial if this cooling system could be provided in a simple and efficient way with a minimum of additional components required.